Jose Mourinho fears some of his Manchester United players do not have the mentality required to make the club successful again.

Mourinho was careful not to identify which players he feels are falling short, but Anthony Martial, Luke Shaw, Jesse Lingard and Chris Smalling are most significant players to have fallen out of favour under Mourinho.

For Martial in particular, the lack of chances has become frustrating, with the player understood to be unhappy at being dropped for Wednesday's 0-0 draw at home to Hull despite setting up two goals in the 4-0 FA Cup victory over Wigan three days earlier.

Mourinho has suggested that some of his players have drifted into a comfort zone, and are satisfied with pushing for Champions League qualification and winning the occasional trophy, having not secured the Premier League title since Alex Ferguson retired in 2013.

The manager added that one of the difficulties he faced after replacing Louis van Gaal in May was working out which of his players were falling short of the standards he demands.

He said: "I didn't know the players very well. I didn't know that some players need time to live with this, because it must be part of your natural habitat.

"Play to win, responsibility to win, cope with the pressure to win. This is something that has to belong to your natural habitat. For some guys, it doesn't.

"They also need that time to go out of their comfort zone or a zone where they are protected that we assume the objective is not to win - that also takes time."